Bearing member having a composite coating



Jan. 14, 1969 D. F. LUNSFORD BEARING MEMBER HAVING A COMPOSITE COATING F iled Dec.

FIG.

FIG.- 2

mvsmon DALLAS F. LUNSFORD BY W fia M ATTORNEYS FIG. 4

FIG. 3

United States Patent Ofiice 3,421,307 Patented Jan. 14, 1969 1nd,, assignor to a corporation of 9 Claims ABSTRACT OF THE DISCLOSURE A ferrous bearing member having an outer coating of a composite oxide formed utilizing a heating and quenching operation, the coating comprising a composite of FO-F304.

This invention relates to a process of forming, from ferrous metals, bearing members which are adapted to be in rotational or reciprocal, frictional sliding contact with other parts and which are subject to substantial wear conditions. More particularly, this invention relates to a novel process for the treating of spinning rings formed from ferrous metal.

It has long been recognized that the life of bearing surfaces in liners, bores, or the like, in conjunction with which moving parts operate, can be greatly increased by providing such bearing surfaces with a hard, durable metal such as hardened steel or chromium. Unfortunately, such surface metals, especially when highly polished, have a tendency to gall, seize or score, particularly when operating under boundary or no lubrication. In addition, under lubricated conditions, it is difiioult to keep such a surface properly lubricated because of the poor oil retention properties of the same.

Many attempts have been made to coat bearing members with materials such as nickel, plastics, nylon and the like which tend to overcome the problem of galling, seizing and scoring. Unfortunately, these surface materials do not have the high wear resistance of the hard metals and are relatively expensive to apply to a bearing member.

It is, therefore, an object of this invention to provide a method of manufacturing a durable bearing member which will not gall, seize or score during operation.

It is another object of this invention to provide a method of placing a composite oxide coating on a fully hardened ferrous article.

It is another object of this invention to provide a process of treating bearing members formed of ferrous metal which inhibits corrosion when such bearing members are exposed to humid atmospheric conditions.

It is another object of this invention to ning ring which substantially increases ring and traveler life.

It is still another object of this invention to provide a spinning ring which allows substantially increased spindle speeds.

Further and other objects of this invention will become apparent from a consideration of the specification and drawings wherein:

FIG. 1 is an isometric view of an induction furnace suitable for coating ferrous articles in accordance with this invention;

FIG. 2 is an isometric view of a typical spinning ring with a traveler attached;

FIG. 3 is a cross-sectional view of a typical spinning ring before a composite coating is placed thereon, and

provide a spin- FIG. 4 is a cross-sectional view of a spinning ring after a composite coating has been applied thereto.

It has been found that a highly desirable bearing member is obtained when a bearing part made of ferrous metal is simultaneously hardened and given a. composite coating of the iron oxides through the process hereafter described.

7 As used herein, the term composite coating is used to denote a coating having a homogeneous blend of the iron oxides integral with an article formed of ferrous metal. Fully hardened ferrous bearing members having such surfaces have been found to perform without seizing, galling or scoring during operation and have exhibited wear rates which give periods of use in excess of standard ferrous bearing members. In particular, good results have been obtained from spinning rings having composite ferrous oxide-ferrosoferric oxide coatings. The good performance obtained from these composite coated spinning rings results not only because of the superior bearing properties provided by the process of this invention, but also because of its inherent resistance to corrosion which is induced by environments normally present in textile mills.

The process of this invention involves heating a ferrous article in a limited oxidizing atmosphere, such as steam, which provides a controlled rate of oxidation. The ferrous article must be heated to a sufliciently high temperature to form ferrous oxide, this temperature being in excess of 1050 F .-After the coating has formed, the ferrous article is quenched either by increasing the flow of oxidizing atmosphere or by dropping the heated article in a medium such as oil or water. At the above reaction temperatures, and with the presence of the limited oxidizing atmosphere, the ferrous article forms a composite coating of FeO-Fe O The quenching then fixes this combination and prevents the FeO from converting to Fe O In addition, this process of heating in an oxygen controlled atmosphere and quenching results in a fully hardened member, if the same is heated above its critical transformation temperature.

The thickness of the composite ferrous oxide-ferrosoferric oxide coating is controlled by time, temperature, type of material and atmosphere. Where a thick coating is required, the temperature and time at maximum temperature should be maintained sufiiciently long to allow complete reaction to the desired coating depth. Conversely, to produce a thin coating, the part would be heated quickly and held at coating conditions for a short period of time.

Referring now to FIG. 1 there is shown an induction furnace 10 suitable for placing a composite ferrous oxideferrosoferric oxide coating, herein referred to as the composite coating, on the surface of a ferrous bearing member or workpiece 12 such as a spinning ring.

The furnace 10 consists of a 'quartz tube 14 having a thin wall thickness. A high frequency induction coil 16 is positioned about the circumference of the bottom portion of the quartz tube 14, the same being made from hollow copper tubing which is kept cool during operation by water flowing within the same. The induction coil is preferably constructed so that it fits tightly about'the quartz tube since the power and efficiency of an induction unit is increased with decreasing distance between the induction coil and the part being inductively heated.

In order to provide a controlled oxidation atmosphere, the top of the quartz tube 14 is sealed with a disk shaped cap 18, which may be made, for example, of Formica, having a circumferential lip 20 which fits over the outside of the top circumference of the quartz tube 22 and having an axially extending opening 24 therein through which it tightly and sealingly receives an inlet tube 26. A steam line 28 is releasably secured to the inlet tube 26, as by a threaded coupling shown generally at 29, so that steam may be introduced into the chamber 30 which is defined by the quartz tube 14 and end cap 18. The bottom 32 of the quartz tube 14 remains open throughout the operation so that a continuous flow of steam may be passed from the inlet tube 26 into the chamber 30 and out the bottom 32 while allowing convenient access and egress to the chamber. The steam pressure within the chamber 30 is maintained somewhat above atmospheric pressure so that air will be prevented from entering the same. The flow of steam is prevented from becoming too great oth' erwise it would tend to cool the bearing member 12 when the same is being heated.

The bearing member or workpiece '12 is supported by a stand 34 made of a non-inductive material such as aluminum oxide, and is placed within the axial and radial center of the coil 16 after which time the workpiece is surrounded by steam which enters the chamber as heretofore explained. After the air within the furnace '10 has been displaced by the steam, the workpiece 12 is inductively heated to a temperature above its critical transformation temperature, i.e., the temperature at which iron will experience a physical change to form austenite, and is austenitized. The critical transformation temperature varies depending upon the type of iron being treated.

Referring now to FIGS. 2-4, the workpiece 12 in this example is a 2" X 1 x spinning ring made of cast iron and has an annular central portion 42 formed with integral top and bottom flanges 44 and 46. The flanges 44 and 46 are annular in form and are axially spaced relative to one another and extend radially inwardly and outwardly from the central portion about the entire circumference, both flanges being adapted to ultimately support a traveler 48. Spinning ring sizes are designated by the inside diameter and width of the flanges 44 and 46 and the height of the ring 12; thus, a 2" x 1 X /8 spinning ring has a nominal inside diameter of 2", a #1 flange which is wide, and has an axial height of Spinning rings 12 are used on spinning frames to guide a body of fibers 50 being twisted into a yarn or thread from feed rolls to a rotating spindle (not shown) by way of a traveler 48 which is mounted to freely rotate about the circumference of each ring. The spinning ring 12 is mounted coaxially with the spindle and reciprocates between the ends of the spindle in a direction of the longitudinal axis of the same to give desired distribution of the spun material thereon. The traveler 48 is usually made from carburized and hardened steel, and rotates circumferentially about the uppermost flange 44.

In the preferred embodiment of this invention the spinning rings '12 are cast from ferrous material of the type commonly referred to as nodular iron i.e., iron having precipitated spheroidal graphite; however, other types of cast iron and other ferrous materials are also contemplated by this invention. The rings of this embodiment were made from a material made in accordance with a similar process to that taught in the United States Patent to K. D. Miller et al., No. 2,485,760. The spinning rings 12 are machined from a nodular iron casting and are simultaneously hardened and composite coated by inductively heating the same in a steam atmosphere for approximately twenty seconds at 1700 F. This temperature is well above the critical transformation temperature of cast iron, the same being approximately 1500 F. The spinning ring 12 which thus has been heated, is then rapidly quenched by discontinuing the inductive power and increasing the rate of steam flowing over the ring so that the temperature of the ring drops quickly. As alternative methods of quenching, the spinning ring 12 may be quickly removed from the furnace and dropped in water or oil immediately after the desired amount of heating has been provided or spray quenched with water or other suitable media before removal. The spinning rings 12 may be quenched to or near room temperature 4 or to some temperatures substantially above the same. The quenching temperature will depend upon the structure desired in the processed workpiece, the methods of obtaining various structure being well known to those skilled in the art.

The power source for the furnace 10 in this preferred embodiment is a 30 kw. motor generator induction unit (not shown) which supplies alternating current of a frequency of 4200 cycles/sec. through water cooled high frequency cables 36 attached to the coil leads 40; the water in cables 36 also provide the cooling water for the coil 16.

A spinning ring manufactured in accordance with this procedure was found to have a minimum surface hardness value of 55 Rockwell C, with the hardness ranging from 55-65 Rockwell C and a coating thickness of approximately 8.0)(10- to 10. 10- inches. The coating 52 which results from this process, as determined by X-ray diffraction, is a homogeneous blend of ferrous oxide and ferrosoferric oxide in approximately equal quantities. These two oxides are similar in structure and appearance, each having an isometric and face centered crystalline structure and each having a black appearance.

It is well known that ferrous oxide (FeO) oxidizes rapidly in the presence of air to form ferric oxide (Fe O The process of this invention results in a surface of substantially homogeneous ferrous oxide (FeO) and ferrosoferric oxide (Fe O which is relatively stable in the presence of air. Although the precise reason for this stability of the FeO which results from the process of this invention is not known, no doubt its presence as a homogeneous portion of a matrix is a factor.

Use of the composite coated rings in a spinning frame leads to longer traveler life, increased production rates, and longer spinning ring life, which results in considerable cost savings. With regard to increased traveler life, in one installation the life of such traveler was increased by a factor of 7.0. The following data resulted from such installation:

circle plated. Normal traveler change cycle 6 days. Traveler change cycle with composite coated ring 42 days.

Alternatively, rather than obtain increased traveler life the rate of production may be increased by using higher spindle speeds. In two other installations, wherein composite coated rings were utilized, traveler speeds were increased while the traveler change cycle remained the same. The results were as follows:

TABLE II Yarn 28s cotton warp. Frame Saco-Lowell Magnedraft. Ring size 2 /2" x 1 X Normal spindle speed 9,250 rpm. Increased spindle speed 10,500 rpm. Normal front roll speed rpm. Increased front roll speed rpm. Normal traveler speed 6,050 f.p.m. Increased traveler speed 6,860 f.p.m. Traveler #10/0 semi-elliptical. Traveler change cycle 120 hours.

TABLE III Yarn 18 /2s synthetic blend warp. Frame Saco-Lowell Magnedraft. Ring size 2 /2" X 1 x /s. Normal spindle speed 9,260 rpm. Increased spindle speed 9,800 r.p.m. Normal front roll speed 145 rpm. Increased front roll speed 154 rpm. Normal traveler speed 6,060 f.p.m.

Increased traveler speed 6,410 f.p.m.

Traveler #2 G1 /2 circle semielliptic. Traveler change cycle 120 hours.

It should be noted at this junction that traveler speeds of the above magnitude cannot be obtained using other available spinning rings even at the cost of reduced traveler life, for too many ends down would be obtained, that is, the body of fibers would break as it passed through the traveler. Increasing the speed of the traveler through the use of composite coated spinning rings did not result in an increased number of ends down.

In a fourth installation, the traveler speed was again increased but an increase in the life of the traveler The increase in traveler life and production rates will vary in accordance with the count and composition of the yarn being spun; therefore, the degree of improvement resulting from the use of composite coated spinning rings will vary accordingly and the above data is intended to be indicative only.

Indications are that the greatest advantage derived from the use of composite coated rings will come from the increase in life of the ring itself and the resistance of such ring to corrosion. In spinning rings having the configuration shown in FIGS. 2-4, travelers are consecutively attached to and operate upon the top flange 44 until such flange wears out, after which the ring is rotated 180' about its diameter and a traveler is attached to the second flange 46 which then becomes the top flange. The first flange 44 will usually last a matter of a few years, but the bottom or second flange 46 has a life of approximately one-half that of the first flange. This is a result of the atmospheric conditions of textile mills which leads to corrosion of the flange 46 while it is in the bottom position prior to its being placed in the top position. I

In order to keep the electrostatic charge of the spinning fibers at a minimum, highly humid atmospheres are maintained around spinning frames. As a consequence of this humid atmosphere, the second flange tends to corrode while the first flange is being used. Because of this corrosion, the period of use of the second flange is substantially reduced. Sometimes the second flange of the prior art spinning rings has to be remachined after removal of the spinning ring from the frame so that it may be serviceable. The first flange does not corrode during this period because the traveler acts as a wiping mechanism during its rotation about the circumference thereof, thereby inhibiting corrosion. Spinning rings with a composite coating have been found not to corrode under these same conditions.

The importance of increased life of spinning rings can be appreciated by the fact that cost of replacing a ring is estimated to equal the purchase price of the same, as reported in the May 1963 edition of Modern Textile on p. 23.

In one test, a bank of spinning rings having two standard steel rings and 16 composite coated rings was operated. After one year the rings were removed and examined. The composite coated rings showed substantially no Wear or corrosion whereas the steel rings not only showed a degree of Wear on the top flange but were also markedly corroded about the bottom flanges.

Although the preferred embodiment of this invention has been shown and described, changes and modifications can be made therein without departing from the scope of this invention, and it is understood that the preceding description is illustrative only and not for the purpose of rendering this invention limited to the details illustrated or described except insofar as they have been limited by the terms of the following claims.

What is claimed is:

1. A bearing member of ferrous metal having an integral coating comprising the combination of ferrous oxide (F c0) and ferrosoferric oxide (Fe O 2. The bearing member according to claim 1 wherein the ferrous metal is hardened.

3. The bearing member of claim 1 wherein said ferrous metal is nodular iron.

4. A spinning ring formed of ferrous metal and having an annular body portion, an annular flange formed coaxially and integrally with said body portion, and provided with an integral composite coating comprising ferrous oxide and ferrosoferric oxide.

5. The ring of claim 4 wherein said ferrous metal is cast iron.

6. The ring of claim 5 wherein said cast iron has been hardened to a minimum of 55 Rockwell C.

7. A spinning ring formed of nodular iron and having an annular body portion, an annular flange formed coaxially and integrally with said body portion, and provided with an integral iron oxide coating.

8. The ring of claim 7 wherein said iron oxide is ferrous oxide and ferrosoferric oxide.

9. An annular bearing member having an exposed peripheral surface adapted to be slidingly engaged comprising an annular ferrous metal member having an integral coating on the exposed peripheral surface thereof of ferrous oxide (FeO) and ferrosoferric oxide (Fe O References Cited UNITED STATES PATENTS 1,745,835 2/1930 Merrill 57-119 1,965,340 7/1934 Heinicke 148-6.35 XR 2,268,868 1/1942 Given 148-635 XR 2,798,357 7/1957 Stahli 57-119 2,987,871 6/1961 Foard 57120 3,226,924 1/1966 Dalpaz 57-119 XR FRANK I. COHEN, Primary Examiner. WERNER H. SCHROEDER, Assistant Examiner.

US. Cl. X.R. 148-6.35 

